ultra-realistic

(masterpiece, award-winning, ultra-realistic, 4K UHD, extremely detailed, hyper-realistic lighting, sharp focus, photorealistic skin texture, natural color depth),
a stunning 18-year-old woman with flowing long white hair, perfect hourglass figure with large breasts, very slim waist, and very large round butt, wearing ultra-thin sheer white leggings tightly hugging her curves and wedged perfectly between her buttocks,
riding an off-road mountain bike through scenic mountains, forest trees and a calm river in the background,
seen fully , squatting on the pedals while holding the handlebar, arching her back and raising her butt upwards,
her round butt clearly visible between the bike seat and the rear wheel, sunlight rim light outlining her curves, subtle motion blur on hair strands,
cinematic outdoor lighting, high contrast, mesmerizing composition, impossible to look away